Laurie: Hey Alfonso! Wait, why are you all sweaty?
Alfonso: I almost missed the bus.
Laurie: What? You're always on time!
Alfonso: Normally, but I forgot to change my clocks after the time change and only realized when I looked at my phone, which updated automatically. I ran to the bus stop, and it was already there, and I barely caught it by the skin of my teeth.
Laurie: Good thing! This bus only runs once an hour!
Meaning: The expression "by the skin of (one's) teeth" means "just barely". This idiom is used when something was extremely close, as in the above example, where Alfonso nearly missed the bus. In addition to just barely doing something on time, "by the skin of (one's) teeth" can also be used to show how close a competition was, as in the next example:
Beatriz: Did you watch the basketball game last night?
Drew: Yeah. I'm so glad our team won, but that finale was intense!
Beatriz: I know! It really came down to the final seconds, but they pulled it off by the skin of their teeth.
Drew: That last shot was amazing!
Meaning: In this example, the basketball team that Beatriz and Drew were rooting for won a game, but in an extremely close match.